A semiconductor storage device includes a circuit receiving a command signal for generating a read control signal (RPB) based on the transition of a clock signal CLK and a circuit receiving the command signal for generating a write control signal (WPB) based on the transition of the clock signal CLK. The read cycle in which decoding of an address, selection of a word line and activation of a sense amplifier are executed based on the read control signal to read cell data, and the write cycle in which decoding of an address, selection of a word line and activation of a write amplifier are executed based on the write control signal and bit line pre-charging is also carried out, are carried out alternately. The sense period of the read cycle is overlapped with the decoding period of the write cycle.